User's Manual
Table Of Contents
EX7100 Technical Manual - Module Descriptions
©1999 Exicom Technologies (1996) Ltd 7-51 Issue 3 - May 2001
7.10 UHF Duplex Filter Module Type 8045
7.10.1 General
The Duplexer allows the receiver and transmitter modules to be connected to one
antenna at each terminal.
This is achieved with selective filtering. At the receive frequency the antenna port of the
Duplexer is connected as directly as possible to the receiver input. Similarly at the
transmit frequency the antenna port is connected as directly as possible to the transmitter
PA output.
The Duplexer is made up of a four cavity notch filter, a Band Pass Band Reject (BPBR)
filter and a Band Reject Band Pass filter (BRBP).
The BPBR is a low pass filter and is connected to the Receiver or Transmitter operating
on the low frequency.
The BRBP is a high pass filter and is connected to the Receiver or Transmitter operating
on the high frequency.
The Duplexer isolates the receiver from the large signals produced by the transmitter. In
addition, it provides significant protection against lightning damage to the radio.
Note: The use of suitable earthing and an external lightning arrester is recommended at
all times, refer to Section 2.6.1 for further details.
The Duplexer covers 406-470MHz with a 9-13MHz Rx/Tx spacing.
UHF Connections
The Duplex filter module has three connection ports: Antenna, High and Low.
Antenna Provides RF connection to/from the installed antenna.
High Connection is dependent on the Tx and Rx operating frequency pair.
If the Tx operates on the higher frequency, the High port connects, via the
BRBP filter, to the PA output (PL102).
If the Rx operates on the higher frequency, the High port connects, via the
BRBP filter, to the Receiver Front-End input (SK101).
Low Connection will be the reverse of that detailed above, dependent on which
module is using the lower frequency.
UHF Mounting
The Duplexer module is externally mounted on the EX7100 terminal Top Cover via 14
threaded studs and associated fasteners (refer to 7.10.5 Duplexer Replacement
Procedure).